Physical Structures for Signal Separation

Abstract: This master’s thesis studies the use of physical structures for signal source separation. A parabolic reflector was used to alter the directional properties of one microphone in a two-microphone array. A method to estimate the mixing channels from measured data is presented, as well as a method to find the optimal separating channels. Measurements of the directional properties and mixing channels in a two-source, two-sensor set-up were made using three reflectors of diameters 10, 5 and 2.5 cm. Speech and noise was mixed with the estimated channels and then un-mixed with the optimal separating channels. The performance of the separation was objectively evaluated, and the results were used to determine the impact of using reflective structures. The results showed that the 2.5 and 5 cm reflectors had very little effect for sound in the voice frequency range, but the 10 cm reflector improved the separation to a certain extent. Thus, there is a potential in using physical structures for signal separation purposes, however the frequency of the sound puts a limit on how small they can be made.